Device for demonstrating the action of the front wheels of automobiles



Sept. 14, 1948. s. R. MILBURN 2,449,499

DEVICE FOR DEMONSTRATING THE ACTION OF THE FRONT WHEELS OF AUTOMOBILES Filed May 9, 1947 INVENTOR.

Arrozmar unbalanced wheels Patented Sept. 14, 1948 UNITED STATE s PATEN DEVICE FOR DEMONSTRATING THE ACTION OF. THE FRONT WHEELS arms or AUTOMO- v Sidney R. Milburn, Mountain View,'N.1.,,assignor to United States Rubber Company, New York, N. Y., a corporation of New Jersey Application may 9, 1947, Serial No. 146.932

mounted.

upon fwhich the tires are tions between these wheels.

The proper setting of. thefront wheels of an automobile, 'bus or truck requires that several different conditions be met. It is hard to explain clearly to otherswhat these conditions are unless equipment gis'available toillustrate how the front wheels of. a motor vehicle run along a road under different conditions of adjustment.

The present invention therefore contemplates a miniature device of simple construction that can be easily adjusted to illustrate how the wheels act in running along a surface when they are set at different angles to each other.

The device of the present invention is extremely well adapted to illustrate'in a simple manner, (1) the mechanism of wheel alignment and (2) the importance of wheel balance.

In order to have even a rudimentary knowledge of the problems involved in wheel alignment for motor vehicles it is necessary to keep in' mind that due to gravity weight exerts its force downward in a vertical direction, and that the weight of a motor vehicle is carried vertically above the 4 cla m (or. 35-13) T 1 oFncEfj.

rea'r'ofsuch axle, which is known as"toe -out,"

also'has an important bearing on the rate of tread wear. The main purpose of toe-in is to eliminate the tendency of the wheels to work or 1 weave towards and from each other in. front of the axle, as a result of any play in the connec The wear caused by excessive toe-in or toe-out can usually be readily identified by visual inspection of the tire tread where it shows up by producing a sharp edge at one side of the tread, anda slight error in point where the tire contacts,the road. This location of the load point can be changed by tiltng the front wheels in a vertical plane and is known as camber. This tilting of the wheels called camber is the means er'nployedby the car manufacturer to decrease the wear on the wheel bearings and the wheel spindle or short axle. Usually the front wheels of an automobile are given positive camber, which means that the wheels tilt outwardly at the top; Negative cam+ ber means that the wheels tilt inwardlyat the top.

It is apparent that too much camber will cause the outside half of the tire tread to do all the work and that this will produce rapid wear upon Conversely too muchv this portion of the tire. negative camber will cause excessive wear upon the inner edge of the tire. It will therefore be seen that camber or the tilting of the front wheels in a vertical plane has an important bearing on the rate of tread wear or miles of service that can be secured from the front tires.

The tilting of the front wheels so that they the toe angle in either direction will produce rapid tire wear.

The foregoing deals briefly with the more important problems concerning wheel allignmenh but, wheel balance is also important; This is the combination of the balance of the wheel, brake drum, tire and tube, and it is highly desirable that the entire assembly be balanced as a unity The balance of such a unit falls into twophases, static balance and dynamic balance. Static balance in a wheel assembly pertains to the equal distribution of inert weight between opposite points, and if the wheel is out of static balance and is supported clear of the ground it will rotate under theinfluence of gravity until the heavy portion of the wheel lies near the ground. Dy-

' namic balance pertains to the proper distribution of the, centrifugal force created by the motion of the wheel, and the lack of dynamic balance of a wheel becomes more noticeable as the speed at which the wheel is rotated increases. V

The present device for demonstrating how to, set properly the front wheels of a motor vehicle is svfdciently small and light in weight to be easily man pulated with one hand, after. the wheels have been tilted to any desired angle, to 1 illustrate how the tires roll along a supporting surface when set to give positive camber or neg.- ative camber or to cause the wheels to toe-in or toe-out. This device may also, be employed to illustrate forcibly how a wheel whichisout of dynamic-balance vibrates when it is; rotated rapidly.

understood from the following description when The various, features of the demonstrating device of the present invention will be further read in connection with the accompanying'dr'awis known as toe-in," or closest together at the ing showing one good practical embodiment of such device, and wherein;

Fig. 1 is a vertical sectional view of the demonstrating device;

Fig. 2 is a side view-of the same device showing the wheels set to produce positive camber; M

Fig. 3 shows how the device of Fig. -1 may be rolled forward by one hand on a supporting" surface to illustrate he toe-in action of the wheels;-

and 1 Fig; 4 isv a face view. of: the. weighted wheel shown in Fig. 1'.

The device of the present'in'vention for demonstrating the action; of the front wheels of a motor vehiclexmay be made in various sizes, but

it has been found in practice that if the main axle l is made about six-inches long it can bea conveniently grasped in one hand as shown in jected to the greatest cessive, furthermore if the wear becomes much greater on the outer portion of the tire thanon its inner portion the tire should be shifted.

Fig. 3 shows the wheels l3 asset witha toe-.in' I adjustment, assinning that where they are closest together is in front of the axleand that when the hand moves in the direction indicated'by 101 Fig. 3 of the drawing. The {axle I 0 is preferably" made from a piece of .metal'tubing' suchias an the arrow-they will roll in aforwarddirection.

If the wheels are rolled forward along a surface warm l i9 n'il s heee a a n the hand in the direction -of thjearrcmrinFi'g. .3

the fact that thistoe-in produces wear upon the dependingv uponthe degreev of toe-in; can

bereadily observed.

rubber tire l5, and the rim M is preferably provided with the slightly spaced annular ribs i8 v which help-tokee'p the bead portions of the tire spaced.

The spindles i i are secured to the oppositeends of the tubular axle [0 by friction universal joints preferably formed of a ball. and socket joint in which the ball I! is an integral portion'of the spindle H as shown. The ball i'l should be slightly smaller in diameter than theinner diameter of thetube l0 and is conveniently prevented from escaping from the end of such tube by spinning the end portion of the tube inwardly as indicated at 18 to reduce the size of the opening of the end of the tube.

The ball I! is preferably held frictionally seated against the annular lip i8 with sufficient pressure to cause the spindle It to remain in any position to which it may be adjusted manually. To this end in the construction shown a thick metal disk I9 is provided within the tubular axle l0 near each end thereof to rest against the ball i1, and an outward pressure is exerted on these disks ill by a coiled sprin confined therebe tween to hold the disks IS in frictional engagement with the balls [1.

The inner end of each hub l2 rests against a shoulder 2| provided upon the spindle II and the wheel is rotatably secured upon the spindle by the head of a screw 22 screwed into the outer end of the spindle l I, the construction being such that each wheel l3 will rotate freely on its spindle or short axle II.

to which the tires l5 are subjected when the.

front wheels are misaligned or out of balance,

and as a result of the construction of the present inventiozf the "wheels l3 may be quickly tilt ed to any desired angle with respect to the main axle M So as to illustrate the effect of positive and negative Camber and also the effect of toein and toe-out setting, and the friction action of the ball and socket joints should be sumcient to cause the spindles to remain in the tilted position to which they are set while the axle I0 is grasped in the hand as shown in Fig. 3 and the wheels are rolled along a flat surface.

Fig. 2 of the drawing shows what is known as positive camber in which the wheels l3 tilt out-- wardly at the top. The effect'of this is to cause the tires to contact the road indicated by the lines X at a point approximately directly below the center of the ball H as indicated by the dot and dash lines Y. It will be seen that when the wheels are given positive camber as shown in Fig. 2 the outer portion of the tire will be sub- Itwi-li be seen from the foregoing that the'demonstrating device of the presen invention is well "adapted to illustrate the who of improper adjustment oralignment of the front wheels-of a motor vehicle,- and the fact that misalignmentcauses rapid wear of the tires.

The present device may also bev employed to illustrate how an unbalanced wheel acts when rotated rapidly, and to this end the right hand wheel shown in Fig. 1 of the drawing has secured to its rim It a weight 23 such as a piece of lead of substantial size that extends outwardly into the hollow-interior of the tire l5, and is conveniently secured in place by crimping the ribs i6 towards each other to grip the weight-23 therebetween. If the axle ill of the demonstrate ing device is grasped in the hand as shown in Fig. 3 so that the wheels iii are held clear of a sup? porting surface, and then the weighted wheel I 3 is rotated rapidly the unbalanced condition of this wheel will be very noticeable since it will cause the tire demonstrating device to vibrate with considerable force.

It will be seen from the foregoing that while the demonstrating device of the present invention is so small that it can be easily manipulated with one hand it will, nevertheless, serve very effectively to illustrate how misaligned crunbalanced wheels adversely'afiect. the wear of the tires mounted on such wheels.

Having thus described my invention what I claim and desire to protect by Letters Patent is:

1. A device for demonstrating the effect of correct and incorrect alignment of the front wheels of a motor vehicle andthe action of camber and toe-in, comprising an axle .a few inches long, a short spindle secured at each end of the axle with a ball and socket friction joint that permits each spindle to be moved to various angles relatively to the axle and be retained by such friction in the adjusted positions, and a wheel and tire upon each spindle, whereby when the axle is grasped in the hand and advanced to roll the tires upon a flat surface the manner in which the tires roll upon the'surface under different wheel settings will be demonstrated.

2. A device for demonstrating the effect of correct and incorrect alignment of the front wheels of a motor vehicle and the action of camber and toe-in, comprising an axle a few inches long, a short spindle secured at each end of the axle with a friction universal joint that permits each spindle to be moved to various angles relatively to the axle and be retained by such friction in the adjusted positions, and a wheel and tire upon each spindle, whereby when the axle is grasped in the hand and advanced to roll the tires upon a flatsurface the manner in which the tires roll upon wear, but this is not serious unlessthe. inclination of the wheelsis' ex 5 the surface under different wheel settings will be demonstrated.

3. A miniature device for demonstrating the I effect of correct and incorrect alignment of the front wheels of a motor vehicle and the action of camber and toe-in, comprising a hollow axle, a

short spindle secured at each end of the axle with 'a ball and socket joint that permit each spindle to be tilted to various angles, a spring confined within the axle and operable to exert friction pressure on the spindle balls to retain them in the adjusted positions, and a wheel and tire upon each spindle, whereby when the axle is grasped in the hand and advanced to roll the tires upon a surface the manner in which the tires r011 upon the surface under different wheel setting 'will be demonstrated.

4. A miniature device for dernonstrating the effect of correct and incorrect alignment and unbalance on the front wheels of a motor vehicle, comprising an axle, a short spindle secured at the tires upon a flat surface the manner in which the tires roll upon the surface will be demonstrated and when the unbalanced wheel is rotated rapidly it will vibrate with considerable force.

, SIDNEY R. MILBURN.

REFERENCES CITED The following references are of record in the file of this patent:'

UNITED STATES PATENTS Number. Name Date a0 1,242,863 Reeves Oct. 9, 1917 Casner' Mar. 16, 1943 

